Saïgon jailbreak beta 3 for iOS 10.2.1 is available now, it appears to have a much better (as stated) success rate, as the developer asks for users to submit a bug report if it fails after more than 10 tries.

Download Saigon Beta3

# Supported Devices

Supports the following 64-bit devices:

iPad Air (Cellular) (10.2)

iPhone 5S (10.2.1) (not tested)

iPhone SE (10.2.1) (not tested)

iPhone 6/Plus (10.2.1)

iPhone 6s/Plus (10.2.1) (not tested)

iPhone 6 (10.3.x) (not yet)

# What's new in Saigon beta3?

significantly better success rate using new exploit (v0rtex)

support for more devices (not tested)

complete re-write of the application

# What's new in Saigon beta 2

Fix for camera not working after jailbreaking

Support for iPhone 6s Plus/iPad Mini 4/iPad Air 2

Minor bug fixes and changes

Slightly better at escaping sandbox

Option to reinstall Cydia by holding 'jailbreak' button then tapping it again

Display device model and version

# How to install Saigon beta3 ipa file?

Download the Saigon .ipa file and Cydia Impactor

Open Cydia Impactor and connect your device

Drag the Saigon.ipa file onto the Cydia Impactor window

Enter your Apple ID (email and password)

Open Settings → General → Profiles & Device Management

Trust the new certificate → open saïgon

Tap 'jailbreak' and enjoy!